Switching between the 'Friends' tab and 'Requests' tab on the friends list sub-menu has always caused the game to hang (while it connects to the server/database that contains the relevant information).

The lag it causes is noticeable to varying degrees, for me it's been getting steadily worse for a while, it causes my screen to hang for around 20 seconds.

Sometimes it will hang long enough to cause a 'not responding' error to occur (this prompts the option to shut the window down or wait for it to respond).

This also occurs to a slightly lesser degree when switching between the staff inventory menu and the main menu, the screen hangs while it retrieves the information listing all the gear you own.

As the friends list grows and the staff inventory list grows the lag gets worse.

..The screen hung for a few seconds, while my game window was still in an unresponsive state the other player accepted the request and immediately sent me an ally request, this appeared to cause my game to crash (it wasn't able to recover from the 'not responding' error).

After I forced the game to shutdown I logged back in, I could see that the player had been successfully added to my friends list but when they tried to send me ally requests I wasn't receiving any pop up notifications prompting me to join.. something's awry.